Disclosed is a medical device and more particularly, a catheter-wire guide assembly that acts as both a cutting and coagulating tool.
Electrosurgical devices are used to rapidly heat tissue. The heating of the tissue can cause a series of concerns for the patient. Heating the tissue can dry it, it can be cut, or heating tissue can cause coagulation.
Cutting occurs when a sinusoidal waveform is continuously applied through the cutting device. Coagulation occurs if the sinusoidal waveform is applied in a series of waveform packets. Depending on the surgeons requirements, the waveform can be altered to suit the purpose of the application.
Electrosurgical devices or units (ESU) can also vary in terms of electrical pathways. For example, the ESU can be operated in a monopolar mode or a bipolar mode. In the monopolar mode, the current generally flows from a relatively small active electrode into the situs, through the body, and returns via a large dispersive electrode. The dispersive electrode can be placed above or below the patient as required. Therefore, in monopolar mode, the current density at the situs is high, causing heat transfer at the situs thereby achieving cutting or coagulation. On the other hand, the current density at the dispersive electrode is relatively low, thereby causing very little heat build-up at the dispersive electrode locale and concomitantly, less or no tissue damage. Fulguration occurs when the active electrode is not in contact with the tissue and sparks fly from the electrode to the tissue. The sparks land on different places on the tissue. Generally to achieve fulguration, a surgeon may select an interrupted current to use, in combination with high voltage (e.g. in the kilovolt range) to break down the air dielectric.
A bipolar ESU has two electrodes between which the current passes. Generally, tissue is placed between the electrodes and current travels between the electrodes and thereby through the tissue. In some embodiments, a traditional bipolar ESU is energized forceps, in which the electrodes are small and cause high current density between the forceps prongs. Therefore, generally there is no large dispersive electrode under the patient used as the passive electrode in current conduction. A large dispersive electrode, if used, is generally to provide an alternate current pathway for safety reasons. In either bipolar or monopolar mode, the current usually jumps via an arc from one electrode to either the other electrode or into the tissue itself.
Therefore, selection of the proper ESU and the proper power will lead to the desired effect. The desired effect is generally a function of the temperature of the heat applied at the situs. For example, body tissue that heats to 45xc2x0 C. can still be cooled back to normal without concomitant tissue damage. However, when the temperature is greater than 45xc2x0 C., then irreversible tissue damage occurs. Between 45xc2x0 C. and 60xc2x0 C., protein damage occurs as proteins lose their quarternary structure and may solidify into a glutinous compound. This process is known as coagulation. Between 60xc2x0 C. and 100xc2x0 C., the tissue dries wherein the aqueous cell contents evaporate in a process known as dessication. Above 100xc2x0 C., the solid contents are reduced to carbon in a process known as carbonization. Therefore, tissue damage is a function not only of temperature, but of duration of exposure to the heat.
Problems associated with ESU surgery include active electrode burns, dispersive electrode burns, explosions of combustible materials, power line shock, muscle stimulation, nerve stimulation, or hidden alternate current pathways. The problems with burns is generally described in Pearce, Geddes, Van Vleet, Foster, and Allen, Skin Burns From Electrosurgical Current, Vol. 17(3), Medical Instrumentation, pg. 226 (May 1983), the disclosure of which is expressly incorporated by reference.
Other problems with ESU surgery include manipulation problems. For example, since the traditional ESU involves many instruments, wires, power sources, etc., there is an increased tendency that wires are crossed, many devices are necessary all of which, which cause overall confusion during the procedure. That many devices are needed, including electrical devices, the incidence of electromagnetic interference with other devices is increased. Since the ultimate result of the electrosurgery often is access to the vascular system, then catheterization procedures are needed. Such procedures also entail many devices such as catheters, wire guides, sheaths, and the like. Therefore, when combining the electrosurgery with catheterization, the number of devices increases dramatically.
The foregoing problems and a technical advance is achieved in the present invention. Disclosed a is medical device in which the wire guide also serves as an ESU.